The present invention relates, in general, to an injection unit for an injection molding machine.
U.S. Pat. No. 6,309,203 B1 describes an injection unit which includes a U-shaped frame having one leg provided for attachment of a load-carrying bracket for a plasticizing barrel, and another leg for attachment of an injection stroke drive. The frame is supported on the machine bed for linear movement. A rotary drive is disposed between the bracket and the injection stroke drive for movement along guide bars which extend parallel to one another between the legs of the U-shaped frame.
German Pat. No. DE 198 31 482 C1 describes an injection unit in which the plasticizing barrel and the injection stroke drive, as well as the rotary drive to rotate the plasticizing screw, are disposed for linear movement on same guide bars which extend at an elevated disposition with respect to the machine bed.
These conventional injection units suffer shortcomings relating to a risk of deformation of the load-bearing elements in view of significant drive and reaction moments generated by the rotary drive and the injection stroke drive during operations. As a consequence, the injection components, i.e. plasticizing barrel and injection drive, become misaligned, resulting in malfunction or even shutdown of the entire injection unit.
It would therefore be desirable and advantageous to provide an improved injection unit to obviate prior art shortcomings and to maintain reliable operation by effectively eliminating misalignments of injection components under load.